1221051240 has 128 divisors (see below), whose sum is σ = 4079376000. Its totient is φ = 324877824.

The previous prime is 1221051233. The next prime is 1221051241. The reversal of 1221051240 is 421501221.

It is a super-2 number, since 2×1221051240² = 2981932261411075200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (1221051241) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 613527 + ... + 615513.

It is an arithmetic number, because the mean of its divisors is an integer number (31870125).

Almost surely, 2^1221051240 is an apocalyptic number.

1221051240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221051240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2039688000).

1221051240 is an abundant number, since it is smaller than the sum of its proper divisors (2858324760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221051240 is a wasteful number, since it uses less digits than its factorization.

1221051240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2576 (or 2566 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 1221051240 is about 34943.5436096570. The cubic root of 1221051240 is about 1068.8365494698.

Adding to 1221051240 its reverse (421501221), we get a palindrome (1642552461).

The spelling of 1221051240 in words is "one billion, two hundred twenty-one million, fifty-one thousand, two hundred forty".